Guys, how do I approach a guy without coming off badly?

I really don't want to come off desperate or slutty to a guy I like. How would you assume a girl would act and approach you in a way where they don't come off slutty or desperate? Don't get me wrong, I have a pretty curvy body (I'm not fat, I know the difference) and I am pretty beautiful (what most people have told me). Some guys I have talked to assumed I wanted to have sex with them just because of how I look.

Updates:

I've never talked to this guy before and we don't even know each other's namesz